One approach, of course, is a tariff with a compensating credit ... if a country imports $50 in cars and components for each $100 they import, they get a 50% credit on tariffs. Phase that in, and give the US carmakers a 5 year deadline ... become viable or die. Within 5 years, European and Asian carmakers will have sorted out which components are the best to source from the US, and the dependency of the US auto industry on the US carmakers would be reduced substantially.
Of course, this is the week in the year when a Buckeye would describe a plan for big chunks of the Ohio car industry to survive while "Detroit" shuts down. Singing, I don't give a damn for the Whole State of Michigan, I'm from Ohio I've been accused of being a Marxist, yet while Harpo's my favourite, it's Groucho I'm always quoting. Odd, that.